Cylindrical device for optical quality control of a strip-like material

ABSTRACT

The invention is for a device for sensing radiation directed from a radiation source on a travelling strip-like sample and radiation reflected from or transmitted through the sample with a rotary cylindrical roller having at least one radiation-transparent sensing point at the periphery of the roller, a central radiation-transparent decoupling point at one end and a central radiation-transparent point at the other end. Inside the roller, there are light guides to guide the radiation from the coupling point to the sensing point(s) and from there to the decoupling point.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a device for sensing radiation from a radiationsource on a traveling strip-like sample reflected from or transmittedthrough the sample.

With certain kinds of products, it seems sensible or even necessary, toperform quality controls during the production, for example with regardto the material composition of the product. Such controls are oftenperformed by means of the interaction of radiation, for example infrared radiation, with the samples to be tested. Thereby the sample isexposed to the radiation and the radiation, transmitted through thesample or reflected from the surface of the sample, is guided to a unitof analysis. Thereby it is desired that, the measures for the qualitycontrol are integrated into the production process in such a way thatthis process is disturbed as little as possible.

2. Description of the Prior Art

In the case of traveling strip-like products, as for example paper andtextile webs, it is known to admit a radiation to the traveling productat a certain position of the path of the product and to capture alargest possible fracture of the reflected or transmitted radiation withradiation absorption devices, which in a fixed position. To make surethat as little as possible of this radiation is lost, it is favorable toguide these radiation absorption devices as close to the sample to betested as possible. If the radiation absorption devices are mounted ontothe traveling sample directly, it leads to the disadvantage of an effectof the friction, which may impair the product.

SUMMARY OF THE INVENTION

It is the task of the present invention to provide a device of the abovementioned kind which guarantees a high effect of the radiation to beanalyzed and which avoids a mechanical damage of the sample to betested.

With a device of the above mentioned kind this task is solved by arotary cylindrical roller, whose periphery contacts the strip-likesample with power conformity and which has at least one radiationtransparent sensing point at the periphery and a centralradiation-transparent decoupling point at one end, and by meanspositioned inside the roller for the transmission of the radiation fromthe sensing point(s) to the decoupling point.

Such a roller can be put into the path of the production of a travelingstrip-like sample without disturbing the production process. When thestrip-like sample is guided via the roller, the radiation absorptiondevices, sensing the radiation to be analyzed, contact the surface ofthe sample. That way the entire radiation, deriving from the partcovered by the sensing point of the surface of the sample, is capturedby the sensing points.

In the running operation of the production the speed of the surface ofthe roller corresponds to the speed of the traveling sample, so thatthere is no sliding friction between the two surfaces. If the radiationis sent to the side of the strip-like sample, which is opposite of theperiphery of the roller, then the radiation transmitted by the sample isanalyzed.

The device according to the invention can also be embodied in such a waythat positioned at the other end of the roller it provides a centralradiation-transparent coupling point, deriving directly from theradiation source, and that is has means for the transmission of theradiation which is directed in via the coupling point, to each sensingpoint.

Hereby the radiation, deriving from the radiation source is sent to thesurface of the sample to be analyzed via the inside of the roller andthe light reflected therefrom is guided back out of the roller to theanalysis.

The device according to the invention can also be embodied in such a waythat at least two of the sensing points on the roller have differentangles of the periphery with regard to the cylinder system ofcoordinates.

That way it is guaranteed, that if the roller turns one single time,several consecutive points, positioned in the direction of the movementof the sample, of the surface of the sample can be examined.

Furthermore the device according to the invention can be embodied insuch a way that at least two of the sensing points on the roller havedifferent heights with regard to the cylinder system of coordinates.

That way measurements via the width of the strip-like sample can beperformed.

The device according to the invention can also preferably be embodied insuch a way that it has means for recording and controlling an absoluteposition of the angle of the roller.

If the absolute position of the angle of the roller is known, then it isknown at the same time which of the sensing points is in contact withthe strip-like sample at this point in time.

The device according to the invention can also be embodied in such a waythat it has at least one fixed induction sensor, which is positioned ina certain radial distance of the axis of rotation and that it has aposition element, turning with the roller, having an effect on theinduction sensor.

Furthermore the device according to the invention can be embodied insuch a way that the position element is a disk with at least oneopening, running directly along the induction sensor when turned.

An advantageous embodiment of the device according to the invention isachieved by a first and a second induction sensor, whereby the inductionsensors have different radial distances from the rotation axis of theroller, and by a position disk, which has at least one perforation onthe position of the radius corresponding to the first induction sensorand at least two perforations on the radius corresponding to theposition of the second induction sensor.

The induction sensor registering the individual perforation sends asignal, when the roller has performed a complete turn. That way theposition of the roller can be calibrated with every complete turn.

An advantageous embodiment of the device according to the invention canalso be achieved by the fact that inside the roller, light guides areprovided for the transmission of the radiation.

That way the formation of the guidance of the path of the rays isespecially simple, as the adjustment of alternative optic elements, asfor example lenses and mirrors, can be avoided.

Furthermore it is advantageous, to embody the device according to theinvention in such a way that the radiation, deriving directly from theradiation source, is coupled in a bundle of input fibers via thecoupling point and the same number of fibers is guided to each sensingpoint.

If the coupling point is evenly illuminated by the radiation source, theparts of the surface of the sample, which are positioned above thedifferent sensing points, are impinged with about the same intensity ofradiation.

Furthermore the device according to the invention can be embodied insuch a way that starting from each sensing point, the same number ofdecoupling fibers are guided into a bundle, leading to the decouplingpoint.

That way, all sensing points are optically connected with the decouplingpoint. As it is generally not possible to perform a separation accordingto the decoupling fibers, deriving from the various sensing points,within the bundle, it seems sensible to chose the belt wrap of thestrip-like sample on the roller in such a way that only one sensingpoint is in contact with the surface of the sample at all times. If theabsolute position of the angle of rotation of the roller is known, thenit is also known which of the sensing points is in contact with thesurface of the sample.

An advantageous embodiment of the device according to the invention canalso be achieved by a cut surface at the periphery of the roller.

The cut surface of the roller guarantees that the sensing points on thesurface of the roller do not cause any unevenness.

Furthermore the device according to the invention can be embodied insuch a way that the roller consists of a carbon fiber intensifiedsynthetic material.

The carbon fiber intensified synthetic material has the advantage of alow density, whereby as against alternative material as for examplespecial steel, the weight of the roller is reduced. Furthermore thecoefficient of expansion of the carbon fiber intensified syntheticmaterial is close to zero, that is why the geometrical sizes of theroller do not change drastically at temperature changes due to theproduction process.

Finally the device according to the invention can be embodied in such away that it has a pushing roller, which presses the strip-like sampleonto the roller.

That way a constant and good contact is guaranteed constantly betweenthe surface of the sample and the surface of the roller.

BRIEF DESCRIPTION OF THE PREFERRED DRAWINGS

In the following an embodiment of the device according to the inventionis illustrated by a representation.

It is illustrated in

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The Figure a schematic illustration of a cross-section through anembodiment of the device according to the invention.

A roller 1 is movably positioned by means of two pinions 2 and 3 in amounting, which is not illustrated here. In its use per definition, theroller is integrated in a rotating way into the production path of atraveling strip-like sample, which is not illustrated here, that thestrip-like sample runs across the periphery of the roller 1. Driven bythe strip-like sample itself, the periphery 4 of the roller 1 gains thesame speed as the strip-like sample, so that between the two kinds ofmaterials no sliding processes occur.

Three sensing points are integrated into the periphery 4 of the roller1, of which only two sensing points 5 and 6 are illustrated in theexample. These sensing points 5, 6 make it possible, for example withthe help of infrared radiation, to test the surface of the strip-likesample with regard to certain characteristics. Hereby the surface of thesample needs to be impinged with a radiation. This is achieved in such away that the radiation, deriving from a source of radiation 7, isfocused onto optical fiber beams 11, with optical instruments such as amirror 8 and optical lenses 9 and 10. The final coupling point 12 of theoptical fiber beams 11 is positioned at the coupling point 13 at the endof the pinion 2. The optical fiber beams 11, which consist of amultitude of input fibers, are guided through the pinion 2 into theinside of the roller. Parts of the beams 14 and 15 from the opticalfiber beams 11 are guided to the sensing points 5 and 6 inside theroller 1, whereby each sensing point 5 and 6 is allocated to the more orless same amount of input fibers, so that both sensing points 5 and 6are impinged with the same intensity of radiation. At the sensing points5 and 6, hemispherical glass objects 15 and 16 are integrated in theperiphery 4 of the roller 1, which are coupled with the parts of thebeams 15 and 16 in an optical manner. These glass objects 15 and 16 arecut together with the periphery 4 of the roller 1, so that there is nounevenness on the surface of the roller in the area of the sensingpoints 5 and 6.

The radiation guided via the parts of the beams 14 and 15 is led via theglass objects 16 and 17 onto the surface of the strip-like sample, whenthe respective sensing point 5 or 6 is just positioned in the area,wrapped by the strip-like sample, of the roller 1. The radiation, led tothe surface of the strip-like sample via the sensing points 5 or 6,interacts with this surface and is then reflected into the glass object16 or 17 again. Besides the part of the beams 14 or 15 of the inputfibers, a further part of the beams 18 or 19 of the decoupling fibers isoptically coupled at each glass object 16 and 17. A part of theradiation, which is reflected from the surface of the strip-like sample,reaches the part of the beams 18 or 19 of the decoupling fibers and isguided through the pinion 3 to the decoupling point 20 at the end of thepinion 3. The radiation emitting at the decoupling point 20 is coupledvia the lenses 21 and 22 in a further light guide 23, which guides theradiation to a unit of evaluation, which is not illustrated here.

The belt wrap of the strip-like sample on the roller 1 and thedistribution of the sensing points 5, 6 are coordinated in such a waythat only one of the sensing points 5, 6 is always in contact with thestrip-like sample. By a measuring system, which is not illustrated here,for the determination of an absolute position of the angle of rotationof the roller 1 it is possible to detect which of the sensing points 5or 6 is just in the wrap area. That way the radiation, registered at thedecoupling point 20 can be definitely allocated to a certain position ofthe surface of the sample.

The sensing points 5, 6 are arranged on the periphery 4 of the roller 1on a spiral line in such a way that the sensing points are distributedevenly along the length of the roller 1, seen in the direction of itsangle of rotation, and that sensing points, positioned in a sequence onthe spiral line, are always separated from each other by the same angleat circumference. With this arrangement of the sensing points 5, 6,measuring profiles can be detected either via the length or via thewidth of the strip-like sample.

List of reference points:

1. roller

2. pinion

3. pinion

4. periphery

5. sensing point

6. sensing point

7. radiation source

8. mirror

9. lens

10. lens

11. optical fiber beams

12. final coupling point

13. coupling point

14. part of the beams

15. part of the beams

16. glass object

18. part of the beams

19. part of the beams

20. decoupling point

21. lens

22. lens

23. light guide

What is claimed is:
 1. A device for sensing radiation directed from aradiation source onto a moving strip-like sample and for sensingradiation reflected from or transmitted through the said samplecomprising:a rotary cylindrical roller having an end portion, an insideportion and a periphery; said periphery contacting said strip-likesample in a manner whereby movement of the said strip-like sample causescorresponding rotation of the said rotary roller; said periphery havingat least one radiation-transparent sensing point located thereon; saidend portion having at least one central radiation-transparent decouplingpoint; and a means located in said inside portion of the roller for thetransmission of radiation from said sensing point to said decouplingpoint.
 2. The device according to claim 1 further comprising:a centralradiation-transparent coupling point directly directed from the saidradiation source; said coupling point located at the end of said rolleropposite said decoupling point; and means for the transmission of theradiation, directed from said coupling point to each said sensing point.3. The device according to claim 1 wherein at least two of said sensingpoints on said roller have different angles at circumference with regardto a cylinder system of coordinates.
 4. The device according to claim 1wherein at least two of said sensing points on said roller havedifferent heights with regard to a cylinder system of coordinates. 5.The device according to claim 1 further comprising means for therecording and controlling of an absolute position of the angle ofrotation of said roller.
 6. The device according to claim 5 furthercomprising at least one fixed induction sensor, said induction sensorbeing positioned in a certain radial distance of the angle of rotationof said roller; and having a position element, said position elementturning with said roller and having an effect on the induction sensor.7. The device according to claim 6 wherein the position element is adisk with at least an opening, said disk running directly along saidinduction sensor when turned.
 8. The device according to claim 7 furthercomprising a first and a second induction sensor, whereby said inductionsensors have different radial distances from the axis of rotation ofsaid roller, and having a position disk, said position disk having aperforation on the radius corresponding to the position of the firstsaid induction sensor, and having at least two perforations on theradius corresponding to the position of the second induction sensor. 9.The device according to claim 1 wherein there are light guides insidesaid roller for the transmission of the radiation.
 10. The deviceaccording to claim 2 further comprising a bundle of input fibers whereinthe radiation, directed directly from the said radiation source iscoupled by said coupling point in said bundle of input fibers andwherein to each said sensing point the same number of fibers is guided.11. The device according to claim 10 further comprising decouplingfibers and a decoupling point wherein from each sensing point the samenumber of said decoupling fibers is guided into said bundle leading tosaid decoupling point.
 12. The device according to claim 1 having a cutsurface at the periphery of said roller.
 13. The device according toclaim 1 wherein said roller consists of a carbon fiber intensifiedsynthetic material.
 14. The device according to claim 1 furthercomprising a pushing roller, said pushing roller pressing the strip-likesample onto said roller.